<?xml version="1.0" encoding="UTF-8" standalone="no"?>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
  <head>
    <meta http-equiv="Content-Type" content="text/html; charset=UTF-8" />
    <title>Replication environment priorities</title>
    <link rel="stylesheet" href="gettingStarted.css" type="text/css" />
    <meta name="generator" content="DocBook XSL Stylesheets V1.73.2" />
    <link rel="start" href="index.html" title="Berkeley DB Programmer's Reference Guide" />
    <link rel="up" href="rep.html" title="Chapter 13.  Berkeley DB Replication" />
    <link rel="prev" href="rep_id.html" title="Replication environment IDs" />
    <link rel="next" href="rep_app.html" title="Building replicated applications" />
  </head>
  <body>
    <div xmlns="" class="navheader">
      <div class="libver">
        <p>Library Version 12.1.6.2</p>
      </div>
      <table width="100%" summary="Navigation header">
        <tr>
          <th colspan="3" align="center">Replication environment priorities</th>
        </tr>
        <tr>
          <td width="20%" align="left"><a accesskey="p" href="rep_id.html">Prev</a> </td>
          <th width="60%" align="center">Chapter 13.  Berkeley DB Replication </th>
          <td width="20%" align="right"> <a accesskey="n" href="rep_app.html">Next</a></td>
        </tr>
      </table>
      <hr />
    </div>
    <div class="sect1" lang="en" xml:lang="en">
      <div class="titlepage">
        <div>
          <div>
            <h2 class="title" style="clear: both"><a id="rep_pri"></a>Replication environment priorities</h2>
          </div>
        </div>
      </div>
      <p>
        Each database environment included in a replication group
        must have a priority, which specifies a relative ordering
        among the different environments in a replication group. This
        ordering is a factor in determining which environment will be
        selected as a new master in case the existing master fails.
        Both Replication Manager applications and Base API
        applications should specify environment priorities.
    </p>
      <p>
        Priorities are an unsigned integer, but do not need to be
        unique throughout the replication group. A priority of 0 means
        the system can never become a master. Otherwise, larger valued
        priorities indicate a more desirable master. For example, if a
        replication group consists of three database environments, two
        of which are connected by an OC3 and the third of which is
        connected by a T1, the third database environment should be
        assigned a priority value which is lower than either of the
        other two.
    </p>
      <p>
        Desirability of the master is first determined by the client
        having the most recent log records. Ties in log records are
        broken with the client priority. If both sites have the same
        log and the same priority, one is selected at random.
    </p>
    </div>
    <div class="navfooter">
      <hr />
      <table width="100%" summary="Navigation footer">
        <tr>
          <td width="40%" align="left"><a accesskey="p" href="rep_id.html">Prev</a> </td>
          <td width="20%" align="center">
            <a accesskey="u" href="rep.html">Up</a>
          </td>
          <td width="40%" align="right"> <a accesskey="n" href="rep_app.html">Next</a></td>
        </tr>
        <tr>
          <td width="40%" align="left" valign="top">Replication environment IDs </td>
          <td width="20%" align="center">
            <a accesskey="h" href="index.html">Home</a>
          </td>
          <td width="40%" align="right" valign="top"> Building replicated applications</td>
        </tr>
      </table>
    </div>
  </body>
</html>
